Tuning problem

Classical Guitar technique: studies, scales, arpeggios, theory
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robk
Posts: 11
Joined: Sun Dec 04, 2016 9:33 pm

Tuning problem

Post by robk » Wed Dec 27, 2017 2:57 pm

When I tune my guitar on the open strings, either by electronic means or by listening to the beats, I noticed that the note A on the third string (2nd fret) is too high compared to the first harmonic of the open 5th string, not a little but almost unbearable. I have noticed this on several (not cheap) guitars. Is this a general problem of guitars? If so, is it common practice to tune the strings depending on the key of the piece that you want to play? (that is, when you play in e.g. Aminor you tune the 3d string a little lower or the 5th string somewhat higher)

Rasputin
Posts: 625
Joined: Fri May 12, 2017 12:25 pm

Re: Tuning problem

Post by Rasputin » Wed Dec 27, 2017 3:26 pm

Yes, that is an intonation issue and is common, though worse on some guitars than others. The discrepancy depends on quite a few things, but I believe string tension and action height are pretty big factors.

When you depress the string you add tension to it, which pulls it sharp, and the more tension there is in the string to begin with, the more you add by depressing it a given distance at a given point. The G string has the highest tension by quite some margin, IIRC, which makes the effect more noticable. You can reduce the discrepancy by using lower tension strings, or by tuning down a bit if you don't need to be a concert pitch. I don't think you can really compensate for it by tuning the open string a bit flat, because the effect is not constant up and down the fretboard, and anyway you are going to want to use the open string at some point.

The basic design of the guitar assumes that when you fret a string, the vibrating length that you are left with is equal to the distance from the fret to the saddle - but this ignores the fact that the string has to rise to get to the saddle (if you put the guitar on its back, the saddle is higher than the fret). This effect should be pretty well compensated for in any well-built guitar, but the compensation is never going to be perfect because the effect varies along the string. You can get guitars with wavy frets that compensate much better (each fret is individually compensated) but are still based on standard 12 tone equal temperament. Those things are a bit zany though, if you ask me.

Rasputin
Posts: 625
Joined: Fri May 12, 2017 12:25 pm

Re: Tuning problem

Post by Rasputin » Wed Dec 27, 2017 3:27 pm

PS, sometimes you can involuntarily pull the note sharp by fretting too hard in a direction that is not quite perpendicular to the fretboard, so check that too.

JohnB
Posts: 647
Joined: Fri Jan 29, 2016 6:17 pm
Location: Bristol, UK

Re: Tuning problem

Post by JohnB » Wed Dec 27, 2017 5:29 pm

This might or might not relate to your problem but the G (third) string is prone to intonation problems due to its greater thickness and hence its greater stiffness (perhaps others will correct me if I am wrong). This is why many luthiers build in compensation at the saddle, which alleviates the issue higher up the fingerboard. But there can also be similar issues at the nut end of the fretboard and compensated nuts exist as well, though I have never used one or seen one in the flesh. (Luthiers can also employ saddle compensation on the other strings, but it is most significant on the G string.)

However, not having any compensation at all on some of my guitars, I find that using a carbon G string significantly reduces the issue with the G string, presumably because it is thinner and more flexible than a nylon G string. It also can eliminate the "tubby" sound that the G string can have on some guitars. - Worth a try.
Last edited by JohnB on Wed Dec 27, 2017 6:01 pm, edited 7 times in total.
Hermanos Conde 1968, Stephen Frith 2007 "Guijoso"

CactusWren
Posts: 86
Joined: Thu Jan 07, 2016 5:50 pm

Re: Tuning problem

Post by CactusWren » Wed Dec 27, 2017 5:55 pm

I have this issue on all of my guitars except my Shelton-Farretta flamenco. It's a 657 mm, I wonder if that's why. I usually make the A's tune to each other, because I find them being off worse than the G being off. If I'm playing a lot of first position C chords with the open G, I will modify it.

mainterm
Posts: 249
Joined: Sun Jan 06, 2008 6:36 pm

Re: Tuning problem

Post by mainterm » Wed Dec 27, 2017 6:31 pm

robk wrote:
Wed Dec 27, 2017 2:57 pm
Is this a general problem of guitars?
Yes. Some guitars more, some less, but all traditionally constructed guitars with standard frets spanning the fingerboard will exhibit subtle tuning problems such as the harmonic you describe - G# @ 4th on 6th string vs. fretted G# on the first string is another example.

Poke around the luthiers area and I'm sure you will find a lot of information about this specifically and intonation generally.
robk wrote:
Wed Dec 27, 2017 2:57 pm
If so, is it common practice to tune the strings depending on the key of the piece that you want to play?
Yes. Each guitar will have it's unique characteristics, and tuning hacks that you develop to get it sounding its best.

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